<!DOCTYPE html>
<html>
	<head>
	<script type="text/javascript">
		function convert() {
			var fromValue = eval(fromVal.value);
			toVal.innerHTML = eval(formula.value).toString();
       }
	</script>
	</head>
	<body>
		<span>fromValue:</span>&nbsp;
		<input id="fromVal" type="text"/><br/>
		<span>formula:</span>&nbsp;
		<input id="formula" type="text"/><br/>
		<input type="button" onclick="javascript:convert();" value="Convert" /><br/>
		<span>toValue:</span>&nbsp;<span id="toVal"></span>
	</body>
</html>